[英]ruby regex match from end of string
I've read somewhere today that regex tag in SO gets most "give me ze code" type questions, so I was cautious in asking... I tried, but if this is a duplicate please let me know so I can delete. 我今天在某地读过,SO中的正则表达式标签最能“给我ze代码”类型的问题,所以我谨慎地问...我试过了,但如果这是重复的,请告诉我,以便我可以删除。
[First]sometext[Second]
I would like to use Regex in Ruby to return value between second []: 我想在Ruby中使用Regex在second []之间返回值:
Second
I so far have: 我到目前为止:
(?<=\[)(.*)(?=\])
which returns 返回
First]sometext[Second
\[.*?(\[)
this grouping will return 这个分组将返回
[First]sometext[
so I've been struggling to somehow mix the two but no luck.. hope someone can help. 所以我一直在努力以某种方式混合这两个但没有运气..希望有人可以提供帮助。
The closest reference I can find in SO was searched with "match second or nth occurence in regex" which I couldn't get it to work on my issue. 我在SO中找到的最接近的参考文献是在“正则表达式中匹配第二或第n次出现”中搜索的,我无法在我的问题上使用它。
my workaround was to use gsub to replace the [First]
with "" to the initial string with: 我的解决方法是使用gsub将
[First]
和“”替换为初始字符串:
\[(.*?)\]
and then do another match.. but I would like know how it can be done with on regex usage. 然后做另一场比赛..但我想知道如何使用正则表达式使用。
> s = "ipsum[First]sometext[Second]lorem"
=> "ipsum[First]sometext[Second]lorem"
> s =~ /\[.*?\].*?\[(.*?)\]/
=> 5
> $1
=> "Second"
There's a lot of ways to handle this. 有很多方法可以解决这个问题。 One that hasn't been mentioned yet is the end of input anchor
$
. 尚未提及的是输入锚点
$
的结束。
s = "[First]sometext[Second]"
s.match(/[\[][^\[]+[\]]$/) # => #<MatchData "[Second]">
s.match(/[\[]([^\[]+)[\]]$/) # => #<MatchData "[Second]" 1:"Second">
This only works in the specific case where [something]
ends your string. 这仅适用于
[something]
结束字符串的特定情况。
The section on 'anchors' describes the subtle differences between $
and \\z
and \\Z
. 'anchors'部分描述了
$
和\\z
和\\Z
之间的细微差别。
http://www.ruby-doc.org/core-2.1.2/Regexp.html http://www.ruby-doc.org/core-2.1.2/Regexp.html
You were close. 你很亲密 Use this to capture the relevant section in the first capturing group, then access it with
$1
使用此选项捕获第一个捕获组中的相关部分,然后使用
$1
访问它
.*?\\[.*?\\[(.*?)\\].*
Here's a way that may be more convenient if you just want the text enclosed by the last [..]
in a string that may contain any number of [..]
's. 如果你只想要一个包含任意数量的
[..]
的字符串中的最后一个[..]
所包含的文本,这可能会更方便。 [Edit: I'll leave this, but @OnlineCop has a better solution for the objective I described in the previous sentence. [编辑:我会离开这个,但@OnlineCop有一个更好的解决方案,我在上一句中描述的目标。 It's also an excellent answer to the original question.
这也是原始问题的绝佳答案。 ]
]
Reverse the string, then search for a substring with a regex that captures ]
in the non-capture group (?:\\])
, captures *.?
反转字符串,然后在非捕获组
(?:\\])
搜索带有捕获]
的正则表达式的子字符串,捕获*.?
in capture group 1 (the ?
making it non-greedy) and captures [
in a second non-capture group. 在捕获组1(
?
使它非贪婪)和捕获[
第二非捕获组中使用。 Lastly, retrieve and reverse the string contained in capture group 1: 最后,检索并反转捕获组1中包含的字符串:
str = "The [first] time I was mad. The [second] time I was irate!"
str.reverse[/(?:\])(.*?)(?:\[)/,1].reverse #=> "second"
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